4. the daily output of energy from the sun is 7.80 x 1027 kcal. convert this energy to
joules (j) & write the answer in scientific notation.

The answer to your question is:  3.276 x 10³¹ Joules

Explanation:

Energy from the sun: 7.80 x 10²⁷ kcal

Look for the factor to convert units

Rule of three to convert units

                   1 cal   4.2 Joules

           1000 cal     x

 x = (1000 x 4.2) / 1 = 4200 Joules

                   1 kcal   4200 Joules

               7.8 x 10²⁷ kcal     x

           x = (7.8 x 10²⁷ x 4200) / 1 = 3.276 x 10³¹ Joules

i think it's letter a.

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)